(1) Storage Area Network
A network which connects one or more computers and one or more external storage apparatuses is referred to as “storage area network (SAN)”. It is a computer system which is often used particularly in the case where a plurality of computers cooperate with one another to provide one function, or in the case where one high-capacity storage apparatus is shared by one or more computers. Storage resources or computer resources can be easily added, deleted or replaced afterward, which provides an advantage of excellent scalability.
(2) Disk Array Apparatus
As the external storage apparatus connecting to the SAN, a disk array apparatus is generally often used. This disk array apparatus is an apparatus including many magnetic storage devices represented by a hard disk. Moreover, the same apparatus manages several magnetic storage devices as one set according to a RAID (Redundant Array of Independent Disks) technique. In addition, this set of the magnetic storage devices is referred to as “RAID group”. The RAID group forms one or more logical storage areas. The computer connected to the SAN executes a data input and output process with respect to this storage area. When data is recorded in the same storage area, the disk array apparatus stores redundant data of one or two of the magnetic storage devices constituting the RAID group. Existence of this redundant data provides an advantage that even in a circumstance where one of the magnetic storage devices has failed, the data can be restored from remaining magnetic storage devices within the RAID group.
(3) Virtual Volume, Virtual Storage Technique
In operations of the SAN, various kinds of storage apparatuses which are different in manufacturer or class may be mixed. In such a circumstance, an operation manager has to perform management such as capacity allocation or volume allocation while caring about properties of the respective apparatuses, which imposes a significant burden. In order to address this problem, there is a virtual storage technique.
A storage virtualization apparatus virtualizes a storage capacity included in a storage apparatus which separately exists, as if it were a resource stored on the same virtualization apparatus, and provides it to a host computer. According to the same technique, management of resources on heterogeneous storage apparatuses with the different properties can be unified, which reduces the burden on the manager.
(4) FCOE (Fibre Channel Over Ethernet (Registered Trademark))
For the network constituting the SAN, Fibre Channel or iSCSI has been mainly used. Moreover, in addition to these communication methods, standardization of an FCOE technique has been newly advanced.
The FCOE is a communication method which has employed the Fibre Channel, instead of using TCP/IP, as a communication protocol, while using Ethernet (registered trademark) as a transmission infrastructure. Thereby, a merit can be obtained that it is possible to utilize assets of the Ethernet (registered trademark) while inheriting a conventional Fibre Channel operation, and in addition, it is possible to enable communication devices of the Fibre Channel and IP to be integrated with the Ethernet (registered trademark) which is the same communication infrastructure.